Millions of individuals suffer from various forms of musculoskeletal disorders, such as bone carcinoma and osteoporosis. When these disorders are not treated properly, they can lead to further complications, some of which may be fatal. The yearly costs arising from musculoskeletal disorders and osteoporosis-related fractures in the United States has been estimated as billions of dollars and these costs are projected to increase. Thus, there is a desire and a need to detect and monitor any changes in bone metabolism to effectively treat bone diseases during the early stages of their development. Bone turnover marker levels reflect such changes in bone metabolism, including instances in which old bone is being replaced with new bone during abnormal bone metabolism. The bone turnover markers are classified as those pertaining to bone formation, which reflects osteoblastic activity; or those contributing to bone resorption, which reflect osteoclastic activity. These markers can serve as a tool to monitor the progression of disease, thus allowing for early treatment to be administered for effective prognosis.
In addition to bone markers, there is a desire in the art to detect and monitor other clinical markers. As an example, tissue clinical markers would serve as a tool to detect and monitor the changes in various organs, such as but not limited to, the heart.
Various conventional analytical techniques are known in the art to detect clinical markers, including ELISA and radioimmunoassay. Although highly sensitive, these techniques suffer from disadvantages of being time consuming, expensive, bulky and requiring skilled personal for operation. The associated disadvantages limit the use of these techniques in hospitals and clinics. Other techniques have been developed to overcome these disadvantages. For example, biosensors have been developed which exhibit quick response times, are less expensive, small, portable, and easy to use, thereby making them amenable to point-of-care testing. There are known in the art fluorescence-based sensing devices and impedence-based sensing devices. In particular, impedance-based devices are extremely sensitive to interfacial binding events occurring at the probe surface.
Among the various materials used in the development of biosensors, carbon nanotubes (CNTs) are suitable materials due to their exceptional mechanical, electrical and surface properties. Further, the approach for CNT growth allows for conditions to be modified to achieve specific properties to fit the needs for sensor integration.
There is a need in the art to develop CNT-based biosensors for the detection of clinical markers, such as bone markers and tissue markers. Further, it is desired to develop biosensors that may be employed ex-situ and in-situ. Furthermore, for in-situ biosensors, it is desired to develop a biosensor that is degradable over a reasonable period of time.